The present invention generally relates to an image forming apparatus. More particularly, it relates to a novel image forming apparatus using a means for respectively reading the duplex faces of an original document and an element having an electric-heat optical effect. Further, it relates to a novel image forming apparatus for filling in image information of a plurality of types of images in a plurality of image filling-in sections, so as to proceed with a process of image forming.
Generally, the conventional image forming apparatus for respectively reading the duplex faces of an original document which transfer the document images onto a transfer paper sheet (for example, the front face and the reverse face of one sheet of transfer paper) is to copy one side face of the original document onto the single face of the transfer paper sheet. This is done through an image forming process composed of exposing, developing, transferring, and fixing steps. Then, the original document is reversed by an RDH apparatus, to simultaneously reverse, transport the transfer paper sheet by the duplex apparatus so as to carry out the image forming process again for copying the other side face of the original document onto the reverse face of the transfer paper sheet.
However, in the conventional image forming apparatus, an optical system for exposing the original document images on an exposure member is composed of an optical apparatus for effecting a slit exposing operation. Also, as a document reversing apparatus such as RDH or a similar apparatus is required, the defects of the conventional apparatus are as follows.
(1) As the document of B5 or A4 size or a similar size is comparatively large in size, only a slit exposure is required so as to expose a sufficient amount of light on the exposure member with a small lens. This occurs so that the image forming speed is not too high.
(2) As a document reversing apparatus such as RDH or a similar apparatus is required, the construction of a document processing section is made larger in scale. As the document is to be transported twice with respect to the document reading section, more time is taken for the document reading, with a high ratio probability that jamming will occur during the document transportation.
In an image forming apparatus such as a conventional copying machine or a similar apparatus, paper sheets with images formed on them are arranged so as to be discharged in order, side by side, and edition by edition, so as to simplify the later processing when a plurality of image paper sheets are formed by plural editions. Therefore, two discharging methods are considered for the apparatus as follows.
(3) One of the methods is to divide the number of editions in the paper-sheet discharging section. One page of document information is to have images formed by the number of the editions, so that they are discharged respectively into the different paper-discharge trays by a sorter. Thereafter, the next page thereof is to have images formed by the number of the editions, so that they are placed on the previous paper-sheet. Through the repetition, one sheet of paper with images formed in it is accumulated one by one on the respective discharge-paper trays.
(4) The other method is to have images formed for each edition. By the use of an automatic feed apparatus for document circulation, as disclosed in U.S. Pat. No. 4,076,408, which is adapted to circulate the document, a plurality of documents are circulated by the number of the required editions so as to form the images in accordance with the document in the course of the circulation. The images are formed one by one, so that a plurality of image-formed paper sheets are accumulated on one stage of the tray.
In an image forming apparatus for forming images on a plurality of copies by the use of a sorter as shown in (3), several bins of discharge paper trays are required to be provided. This creates a disadvantage of a larger apparatus, and a complicated paper-sheet discharge control. Also, in an image forming apparatus using an automatic feed for the document circulation as shown in (4), the document is circulated by the number of the editions, such that the document is likely to be damaged and the probability of causing jamming becomes higher.